Further memory protections committed to -current

In a long series of commits, Theo de Raadt (deraadt@) has added support for the immutable memory mappings on which we reported earlier. We see:

CVSROOT:	/cvs
Module name:	src
Changes by:	deraadt@cvs.openbsd.org	2022/10/06 21:20:58

Modified files:
	sys/sys        : exec_elf.h 

Log message:
Add identifiers for the new "mutable bss" section, ".openbsd.mutable" is
0x65a3dbe5.  Also add PF_MUTABLE as a segment flag for later use.

and:

CVSROOT:	/cvs
Module name:	src
Changes by:	deraadt@cvs.openbsd.org	2022/10/06 23:01:44

Modified files:
	sys/uvm        : uvm.h 

Log message:
new UVM_ET_IMMUTABLE flag marks a uvm entry as immutable.

and:

CVSROOT:	/cvs
Module name:	src
Changes by:	deraadt@cvs.openbsd.org	2022/10/07 08:59:39

Modified files:
	sys/kern       : exec_subr.c kern_exec.c kern_pledge.c 
	                 kern_resource.c syscalls.master 
	sys/sys        : mman.h 
	sys/arch/mips64/mips64: trap.c 
	sys/uvm        : uvm_extern.h uvm_io.c uvm_map.c uvm_map.h 
	                 uvm_mmap.c 

Log message:
Add mimmutable(2) system call which locks the permissions (PROT_*) of
memory mappings so they cannot be changed by a later mmap(), mprotect(),
or munmap(), which will error with EPERM instead.
ok kettenis

and:

CVSROOT:	/cvs
Module name:	src
Changes by:	deraadt@cvs.openbsd.org	2022/10/07 09:04:52

Modified files:
	gnu/llvm/lld/ELF: ScriptParser.cpp Writer.cpp 
	gnu/llvm/llvm/include/llvm/BinaryFormat: ELF.h 
	gnu/usr.bin/binutils/bfd: elf.c 
	gnu/usr.bin/binutils/binutils: readelf.c 
	gnu/usr.bin/binutils/include/elf: common.h 
	gnu/usr.bin/binutils/ld: ldgram.y 
	gnu/usr.bin/binutils-2.17/bfd: elf.c 
	gnu/usr.bin/binutils-2.17/binutils: readelf.c 
	gnu/usr.bin/binutils-2.17/include/elf: common.h 
	gnu/usr.bin/binutils-2.17/ld: ldgram.y 

Log message:
In the linkers, collect objects in section "openbsd.mutable" and place
them into a page-aligned region in the bss, with the right markers for
kernel/ld.so to identify the region and skip making it immutable.
While here, fix readelf/objdump versions to show all of this.
ok miod kettenis

and:

CVSROOT:	/cvs
Module name:	src
Changes by:	deraadt@cvs.openbsd.org	2022/10/07 09:21:04

Modified files:
	lib/libc       : Symbols.list shlib_version 
	lib/libc/hidden/sys: mman.h 
	lib/libc/sys   : Makefile.inc mmap.2 mprotect.2 munmap.2 
Added files:
	lib/libc/sys   : mimmutable.2 

Log message:
Add mimmutable(2) libc stub, add & adjust manual pages, and crank the minor.
ok kettenis

and:

CVSROOT:	/cvs
Module name:	src
Changes by:	deraadt@cvs.openbsd.org	2022/10/07 09:22:10

Modified files:
	usr.sbin/procmap: procmap.1 procmap.c 

Log message:
Show the entry immutable bit in the various output formats.

These commits provide an early preview of what could be one of the major changes in a future release, likely OpenBSD 7.3. Testing, early and often, is always welcome.